Esters of mixtures of polyoxyalkylene monohydroxy compounds



reacted Aug. 30, 1949 ESTERS F MIXTURES 0F POLYOXYALKYL- ENE MONOHYDROXYCOMPOUNDS H arvey R. Fife, Mount Lebanon, Pa., and Frederick H. Roberts,Charleston, W. Va., assignors to Carbide and Carbon ChemicalsCorporation, a corporation of New York No Drawing. Application July 25,1947, Serial No. 763,746

. 1 This invention relates to esters of mixtures of aliphatic monoethersor polyoxyalkylene glycols. It is particularly concerned with esters ofthose mixtures having relatively high average molecular weight, andcomprising molecules containing polyoxyalkylene chains formedpredominantly of the oxyethylene group, OC2H4-, and the oxy1,2-propylene group, -OC2H3.CHa-. Such mixtures may result, forinstance, from the reaction of monohydroxy aliphatic alcohols withalkylene oxide mixtures containing, for the most part, ethylene oxideand1,2-pr opylene oxide, The mixtures of aliphatic monoethers withpolyoxyalkylene glycols are more fully described in our copendingapplication Serial No. 538,340 filed June 1, 1944, now Patent No.2,425,755, of which this application is a continuation-in-part.

The mixtures of monohydroxy alcohols which are esterified according tothe, present invention may be obtained by the addition, to a monohydroxyaliphatic alcohol, of a mixture of alkylene oxides containing ethyleneoxide and 1,2-propylene oxide in an oxide ratio from 75-25 to -90ethylene oxide to 1,2-propylene oxide. By oxide ratio from 75-25 to10-90 is meant that, in the oxide mixture which may be used in formingsuch monohydroxy alcohol addition product, the amount of 1,2-propyleneoxide in the mixture is from one-third to nine times the amount ofethylene oxide present, by weight, the parts or proportion of the1,2-propylene oxide being given last.

The reaction which takes place between the alcohol and the ethyleneoxide and the 1,2-propylene oxide seems to be a simple addition whereinthe alkylene oxide molecules undergo conversion to the correspondingoxyalkylene radicals as i1- lustrated for any given molecule by thefollowing general equation:

R M 1110) 1( H|.GaH|0) -v B10031). 0H

Alcohol Ethylene 1,2- m ylme Addition oxide ox is product where ROHis analiphatic monohydroxy alcohol;

6 Claims. ,(Cl. 260410.6)

y and 2 represent the mols of ethylene oxide and 1,2-propylene oxiderespectively; n is both 2 and 3 in a single molecule, the total numberof times 11. has a value of 2 being equal to y and the total number oftimes 11. has a value of 3 being equal to z; and a: is the total numberof such oxyalkylene groups, being equal to y+z.

From such properties as the average molecular weight, refractive index,density, viscosity, rate of change of viscosity with change intemperature, as well as upon theoretical considerations, it appears thatthese products are complex mixtures of monohydroxy polyoxyalkylenealiphatic ene groups are present therein; and in a mix-- ture of suchcompounds the average molecular weight attributable solely to theoxyalkylene chain would be between 234 and 276 with the oxide ratiocorresponding thereto being between 75.2-24.8 and 15.9-84.1. Similarly,the molecular weights of the oxyethylene-oxy 1,2-propylene chains ofcompounds having six oxyalkylene groups to the molecule with two, three,four and five oxy 1,2-propylene groups present therein would be 292,306, 320 and 334, respectively; and in mixtures of such compounds theaverage molecular weight attributable solely to the oxyalkylene chainwould be between 292 and 334 with an oxide ratio between 60.3-39.7 and13.2- 86.8 corresponding thereto. Compounds having a single oxypropylenegroup are omitted since their oxide ratio falls definitely above the -25limit. In compounds having a total of seven oxyethylene and oxy1,2-propylene groups to the molecule, of which the number of oxy1,2-propylene groups are two, three, four, five and six, the molecularweight of the polyoxyalkylene chain would be 336, 350, 364, 378 and 392,respectively; and in mixtures of such compounds theaverage molecularweight attributable solely to the polyoxyalkylene chain would be between336 and 392, with an oxide ratio between 65.5-34.5 and 11.2- 88.8corresponding thereto. -Likewise, in compounds having two, three, four,five, six and seven oxy 1,2-propylene groups in an oxyethylene oxy1,2-propylene chain of eight oxyalkylene groups, the molecular weightsof such chains would be 380, 394, 408, 422, 436 and 450 respectively,with the average molecular weights attributable to the polyoxyalkylenechain in a mixture of such compounds being between 380 and 450, and theoxide ratio corresponding thereto being between 69.5-30.5 and 9.8-90.2.To each of the foregoing values for molecular weights and averagemolecular weights, there is to be added a value not less than 32, themolecular weight of methanol, the lowest member of the aliphatic alcoholseries.

A product containing in admixture the monohydroxy aliphatic monoethersof the foregoing polyoxyalkylene chains, having proportions between75-25 and -90, would have as many as nineteen constituents (exclusive ofisomers) which difier from one another in the molecular weightsattributable to the polyoxyalkylene chains yet which have a spread ofonly from five to eight oxyalkylene groups between the smallest andlargest molecules, and a spread of from 266 to 482 in the molecularweights of the methyl monoethers, The complexity of the mixture may bedue not only to the diflerence in molecular weights of the chains butalso to the large number of isomers which may be formed by random (i.e., interspersed) distribution 01' the oxyethylene and oxy 1,2-propylenegrou s, with consequent variations in internal configuration frommolecule to molecule, even among those of the same molecular weight.-The complexity increases with molecular weight. These products may bereferred to as mixtures of monohydroxy heter zed oxyethylene oxy1,2-propylene aliphatic monoethers, and by the term heterized we meanthat the monoethers vary in internal configuration from molecule tomolecule, such variation arising out of a randomness of the distributionof the oxyethylene and the oxy 1,2-propylene groups therein, such asresults, for instance, from the concurrent reaction of ethylene oxideand 1,2-propylene oxide with an aliphatic monohydroxy alcohol.

Using ethylene oxide-1,2-propylene oxide ratios from 75-25 to 10-90 byweight, and starting alcohols having one, two, three, four and morecarbon atoms to the molecule, we have made a number of products havingaverage molecular weights ranging from about 500 to upwards of 5,000.They may be obtained as normally liquid products which are characterizedby having a relatively low rate of change of viscosity with change intemperature; the actual viscosity of the product as well as such otherproperties as density, refractive index and the like being dependent onthe starting alcohol, the oxide ratio and the average molecular weight.For a given starting alcohol and oxide ratio, the viscosity, density andrefractive index increase with molecular weight, and, for alcoholshaving from one up to fourteen or more carbon atoms, and for oxideratios from 75-25 to 10-90, the viscosities at a given temperatureappear to lie in a relatively narrow band or zone which, at atemperature of 210 F., extends from 3 to 10 centistokes at averagemolecular weights of about 500 to 800, up to 20 to 50 centistokes ataverage molecular weights of about 1,500 to 2,000. For oxide ratios from50-50 to 10-90, at a temperature of 20 F., the viscosities extend from150 to 500 centistokes at average molecular weights of about 500 to 800,up to 1,500 to 5,000 centistokes at average molecular weights of 1,500to 2,000.

- In general, products made from oxide mixtures having a higherproportion of ethylene oxide than of propylene oxide exhibit asubstantially greater. degree of miscibility with water, or a greaterwater-tolerance, than those made from oxide mixtures containing apreponderance of 1,2-propylene oxide. By way of illustration. a butyl'monoether having an oxide ratio of 50-50 made by our preferred method,under water-free conditions using an alkali metal hydroxide as catalyst,is characterized by the unusual property of being miscible with coldwater up to about 50 An aquea product separates into two layers attemperatures of about 40 to 60 C. or higher. The one layer is a solutionof water in the product and the other layer is a solution of the productin water. With increase in the 1,2-propylene oxide content thewater-tolerance of the product decreases, and at an oxide ratio of25-75, for instance, the products are substantially immiscible withwater, even at low temperature; except possibly at low average molecularweights. On the other hand, products made from ethyleneoxide-1,2-propylene oxide mixtures in oxide'ratios from 75-25 to 60-40may require a temperature of about -100 C. or even higher to cause theseparation of two layers from aqueous solutions of the products, but thetemperature at which separation may take place in any particular casewill depend upon a number of factors including the average molecularweight, the starting alcohol, and to some extent, the conditions underwhich the product is made.

Products made from mixtures having oxide ratios from about 50-50 to10-90 are also characterized by the very useful property of remaining inthe fluid state at low temperatures as low as '--50 C., and below. Thetemperature at which solidification of the product takes place increaseswith increase in'ethylene oxide content above 50 per cent. Products madefrom mixtures having oxide ratios from 75-25 to 60-40 usually contain asolid phase at temperatures as high as 0 0; Even at temperatures above10 0., presence of a solid or crystal phase may be observed by thehaziness or cloudiness of the mixture, but the temperature at whichsolidification may take place in any particular case will here againdepend upon a number of factors including the average molecular weight,the starting alcohol and to some extent, the conditions under which theproduct is made.

Methods of preparing the aliphatic monoethers of polyoxyalkylene glycolswhich are ester: ified in accordance with the present invention aredescribed in our copending application Serial No. 538,340, filed June 1,1944, now Patent No. 2,425,755.

According to this invention, mixtures of aliviscosity than the originalmonoethers.

phatic monoethers oi polyoxyalkylene glycols containing both oxyethyleneand oxy 1,2-propy1-.

ene groups in the molecule and having an average molecular weight or atleast 500 by acetyl values attributable to said groups, are partially orcompletely esteriiied with organic carboxylic acids consisting solely ofthe elements carbon, hydrogen and oxygen and having up to two carboxylgroups to the molecule and from 2 to 20 carbon atoms in the molecule.Esterification of these polyoxyalkylene glycol monoethers withcarboxylic acids results in an important modification oi the propertiesof the monoethers. In general, esters corresponding to the monoetherswhich are soluble in cold water are relatively insoluble in both hot andcold water. In this property the esters of the present invention differfrom the esters of high-molecular weight polyoxyethylene glycols ortheir monoethers which esters are usually water-soluble. Also, theesters of those polyoxyalkylene glycol monoethers which are insoluble incold water have reduced capacity to absorb water.

Esteriflcation of mixtures of aliphatic monoethers of polyoxyalkyeneglycols containing both oxyethylene and oxy 1,2-propylene groups in themolecule also changes their viscosity; the degree and direction of thechange depending on the type of carboxylic acid esterified.Esterification of the monoethers with a dicarboxylic acid, such assuccinic, adipic or'phthalic acids, results in esters having a higherviscosity than the original polyoxyalkylene glycol monoethers.Esteriiication oi! the monoethers with a lower aliphatic monocarboxylicacid, such as acetic acid, buiwric acid or 2-ethyl hexanoic acid,results in esters having a lower viscosity than thestarting material. Onthe other hand, esterification 01 the monoethers with a higherfattyacid, such as stearic acid, results in esters having a' higher Ingeneral, the monoether aliphatic esters exhibit less change in viscositywith change in temperature than do the monoethers; in other words, themonoether aliphatic esters have ahigher visters wet metal surfaces morereadily and are adsorbed thereon to a greater degree than themonoethers, making the monoether esters improved lubricants for metal.

Esterification of the monoethers may be carried out by reacting themonoethers either with the free carboxylic acids, or the correspondinganhydrides or acyl chlorides. Ester exchange reactions may be carriedout with glycerides. such as castor oil.

The followihg examples will illustrate the invention. A

EXAMPLE 1.&Acsrars Es'rsss General procedure The starting material was areaction product of butanol with a mixture of ethylene oxide andpropylene oxide having an oxide ratio 01 50, the reaction product havingan average molecular weight of 2545 and a viscosity at F'. of 278.5centistokes. Four hundred and seventyflve (475) grams (0.187 mole) ofthis material were placed in a glass reaction vessel equipped with astirrer, an ebullition tube for introducing gases, and a distillationcolumn, and 16.1 grams (0.205 mole) of acetyl chloride were addeddropwise over a period of 15 minutes -while maintaining the temperaturein the vessel at 35 to 49 C. The charge was stirred for three hours tocomplete the reaction. At the end of this time, nitrogen was introducedthrough the ebullitiontube, and hydrogen chloride and excess acetylchloride were stripped from the product at a pressure of 41 mm. Hgabsolute pressure and a final kettle temperature of 153 0.,Saponification showed that the product contained 97% by weight of theacetate ester, and the product had a viscosity of 230 centistokes(cstks) at 100 F.

The acetate esters of a number of related butyl monoethers havingdiiferent oxide ratios, and varying molecular weights were preparedin'a.similar manner. Certain properties of these butyl monoethers and theiracetate esters are cosity index. Furthermore, the monoether.vestabulated below:

Butyl Monoethen Acetatss oi Butyl Moncethers Visc., Centistokes Vise,(entistokes M01 wt Visc. Ratio Run Vise. Ratio 100 F. [210 F. No. 100 F.[210 F. I

100 F. 210 F. 0 1'. 100 F. 210 F. 0 F.

' OXIDE RATIO 75-25 OXIDE RATIO 50-50 OXIDE RATIO 25-75 OXIDE RATIO10-90 other properties of the acetates of the mono- Analysis of theproduct by saponiflcation butyl ethers are given below: I showed that itcontained 97% by weight of the Acetates of butyl monoethers Misc. TemVisc- Ab 0101 Vise Index r1555 withE us? 130 5511 A. s.' 'r. M. Pointvolume ivlin- Ram 3, 535 (m $93 D-567-41 F. e i-al 011 1381 1 0560 1.4546 165 406 182 3268 1 0814 1.4630 139 406 M 1456 1 0399 1.4527 160 417167 1589 1 0336 -l. 4522 159 423 157 2583 1 0505 1. 4580 145 446 3303 10515 1.4582 139 408 200 3575 1 0535 1.4592 135 426 200 1471 l 01571.4496 154 397 1% 3161 l 0286 1. 4543 139 410 176 1875 1 0064 1.4493 154399 109 2237 1 0110 1.4507 143 428 125 I Miscibilitytemperature=temperature at which equal volumes are miscible.

In addition to their utility as metal lubricants, Z-ethylhekanoate estemIt h a viscosity of the acetates of the butyl monoethers are useful 52.2centistokes at 100 F.

as plasticizers for nitrocellulose. The 2-ethylhexanoate esters ofseveral related v EXAMPLE 2 2 ETHYLHEXANOATE.ESTERS butyl monoethershaving diilferent oxide ratios and varying molecular weights wereprepared in a.

General Procedure similar manner. Certain properties of these Thestarting material was a. reaction product butyl monoethers and their2-ethylhexanoate esof butanol with a mixture of equal parts by weighttors are tabulated below:

Butyl Monoethers 7 1 z-Ethylhexanoates of Butyl Monoethers Visa,Centls'tokes vi R Visa, Oontistokes Vi R u SC. 810. 1111 S0. 8 0 RamF./210 F. No. 100 F./2l0 F.

100 F. 210 F. 100 1*. 210 F.

1525 1,365 111.5 20.5 5.44 1 100 10.1 5. 24 50-50 912 53.0 10.55 5.05 252.2 10.0 4.02 50-50 2, 455 885 a 785-815 r 0.05 10410 555 21.4 4.1 4.504 20.5 4.78 I 4.25 10-00 1,808 111. 0 20.2 5.01 5 152 26.8 5 55,

l Centipoises.

of ethylene oxide and propylene oxide having an Other properties of theZ-ethylhexanoate esters average molecular weight of 912 and a viscosityof the butyl monoethers are given below:

Z-ethylhemcnoates of butyl monoethers D. Vlsc. Misc. Temp.

of 53.9 centistokes at 100 F. Four hundred (400) The 2-ethylhexanoateesters of the butyl monograms (0.44 mole) of the resulting mixture of 60ethers are valuable as crankcase lubricants for butyl monoethers'wereplaced in a glass reaction internal combustion engine. In general, theseesvessel equipped with a stirrer, an ebullition tube ters are moremiscible with mineral oils than are for introducing gases, and adistillation column, the acetate esters of the previous example. The and90.1 grams of a mixture of Z-ethylhexanoic miscibility of the2-ethylhexanoate esters of the acid (30%) and 2-ethylexanoyl chloride(70% 65 butyl monoethers with mineral oil increases with correspondingto 0.385 moles of the acid chloride the proportion of oxypropylenegroups in the were added, dropwise, over a period of an hour molecule,and decreases with the molecular at 36 to 42 C. The temperature in thevessel was weight.

then reduced to 26 C. and maintained there for 5 hours. The temperaturein the kettle was then 70 EXAMPLE 3.S'ruARArn Esrrms slowly raised to147 C. and hydrogen chloride and excess acid and acid chloride were thenstripped General procedure from the vessel at 15 mm. Hg absolutepressure with theaid of carbon dioxide which was intro- The reactionvessel was made of glass and was duced through the ebullition tube. 7equipped with a stirrer, a reflux condenser and temperature of theliquid was then increased to 1 125 C. and 70 cc. of benzene removed fromthe system. After cooling to 87 0., 151 grams (0.5 mole) of stearylchloride were added dropwise over a period of 3 hours at about 70 C.Heating of the charge was continued for 7 hours at 60 to ebullition.

There was recovered 548.7 grams of the stearate ester, a yield of 91.5%based on the butyl monoether charged. The product analyzed 100% stearateester by saponification. It had a viscosity of 70.1 centistokes at 100F.

By a similar procedure, other stearate esters of other butyl monoetherswere prepared. The physical properties follow:

Examrnr 4.--Bruzom Esme General procedure 1'0 400 grams (0.44 mole) ofthe butyl mono- 5 'ethers of oxyethylene oxy 1,2-propylene glycola.

having an oxide ratio of -50, an average molecular weight of 912 and aviscosity of 53.9 centistokes at 100 F'., in a vessel as describedpreviously were added 66.6 grams (0.474 mole) of benzoyl chloride,dropwise, over a period of 25 minutes at 31 to 39 C. The charge wasstirred for eight hours. Then the free hydrogen chloride and unreactedbenzoyl chloride were removed by bubbling carbon dioxide through theliquid, and

stripping the product to a liquid temperature of 158 C. at an absolutepressure of 26 mm. of Hg. The reaction product contained by weight esterby saponificatlon analysis, and a portion of the product was esterifledfurther as follows:

To 257 grams of the above product (containing 0.1 mole of unreactedbutyl monoethers) were added 15.5 grams (0.11 mole) of benzoyl chloride.dropwise, over a period of about one hour at 52 to 77 C. The charge wasreacted for (10) ten hours at 65 C., and then stripped of volatileconstituents at about 20 mm. of Hg absolute pressure to a final liquidtemperature of 160 C. A

- total of 261 grams of product was obtained,

analyzing benzoate ester by saponlfication Butyl Monoethers Steal-atesof Butyl Monothers Visc., Centistokes Viso., cenusmre Oxide Ratio M01.Visc. Ratio Run Visc. Ratio Wt. 1GP F.I210 F. N0. F./210 F.

111)" F. 210 F. 100 F. 210 F.

1 Centipoises.

Other physical properties 01' the stearates or the butyl monoethers aretabulated below:

Stearates of butyl monoethers analysis. Two other benzoate esters ofrelated butyl monoethers were also prepared, the prod- The stearateesters of the butyl monoethers are useful as gear oils, textilelubricants, emulsifying agents and as lubricants in metal drawing.

ucts containing 92 to 97% benzoate ester by weight. The physicalproperties of these preparations follow:

Bntyl Monoethers Benzoates oi Bntyl Monoetherl Vlsc., Centistokes v R uB Visa, Centistokea vac m 18C. 8 0 1111 100 F./210 F. No. 100 r4210 1'.

100 1. 210 F. 100 F. 210 F.

Benzoates of butyl monoethers Misc. Tem S .V c. Refracfi'z Oxide 15.11.39 $2 8 3? tive Vise. 62 332 Ram fgl g 0. 8 Mineral on,

- sAEao, =0

I suitable as lubricants than are the aliphatic esters.

EXAMPLE 5.SUcc1NArE ESTER There was charged to a glass reaction vesselequipped with a stirrer, reflux condenser and decanting head, 461.5grams (0.5 mole) of the butyl monoethers of oxyethylene oxy 1,2-pr0-pylene glycols having an oxide ratio of 50-50, an average molecularweight of 912 and a viscosity of 53.9 centistokes at 100 P. Then 300 cc.of benzene were added and the mixture refluxed about 7 hours at a liquidtemperature of 93-95 C. to remove small amounts of water azeotropically.At the end of this period, 54 cc. of benzene was removed by distillationat a liquid temperature of 96 C. The addition of 38.7 g. (0.25 mole) ofsuccinyl chloride was then made, dropwise, over about one hour at 93-960., followed by heating at the same temperature for about 6 hours. Theproduct was then stripped of benzene and hydrochloric acid under 20 mm.pressure to a liquid temperature of 170 C. Carbon dioxide was used forebullition during this latter operation. A total of 474 grams of productwas obtained. The product contained 96% by weight of the (ii-esters ofsuccinic acid by saponification analysis.

The physical properties are tabulated below.

1. Esters of a mixture of monohydroxy oxyethylene oxy 1,2-propylenealiphatic monoethers in which the aliphatic monoether group has from oneto fourteen carbon atoms and in which the ratio of oxyethylene groups tooxy 1,2-propylene groups combined in the molecule ranges from 3 to 1 to1 to 9 by weight and in which said groups contribute at least 500 to themolecular weight of said mixture, with an organic carboxylic acidconsisting solely of the elements carbon, hydrogen and oxygen and havingfrom one to two carboxyl groups and from 2 to 20 carbon atoms to themolecule.

2. Esters of a mixture of monohydroxy oxyethylene Oxy 1,2-propylenebutyl monoethers in which the ratio of oxyethylene groups to oxy1,2-propylene groups combined in the molecule ranges from 3 to 1 to 1 to9 by weight and in which said groups contribute at least 700 to themolecular weight of said mixture, with an organic carboxylic acidconsisting solely of the elements carbon, hydrogen and oxygen and havingfrom one to two carboxyl groups and from 2 to 20 carbon atoms to themolecule.

3. Esters as defined in claim 2 in which the acid is an aliphaticmonocarboxylic acid containing from 2 to 18 carbon atoms.

4. Esters as defined in claim 2 in which the acid is acetic acid.

5. Esters as defined in claim 2 in which the acid is z-ethylhexanoicacid.

Butyl Monoethers I Succinate of Butyl Monoethers Visc., Oentl- IVisc.,'Centl- Oxide Mol. mm Vise. Ratio mm Visc- Ratio Ratio Wt. 100F./210 F. 100 F.l210 F.

100 F. 210 F. 100 F. 210 F.

Succinate of butyl monoethers Specific viscosity benzene solution, 18 C.2705 is S acid Misc. temp. with equal volume mineral oil,

SAE 30, C. 200

The succinate esters of the butyl monoethers are useful as plasticizersand as textile lubricants.

We claim:

6. Esters as defined in claim 2 in which the acid HARVEY R. FIFE.FREDERICK H. ROBERTS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name A Date Kessler Dec. 10, 1929 Goldsmith Jan.13, 1942 Number Certificate of Correction Patent N 0. 2,480,185 August30, 1949 HARVEY R. FIFE ET AL. It is hereby certified that error appearsin the printed specification of the above numbered patent requiringcorrection as follows:

Column 11, Example 5, in the table, seventh column thereof, for 31.3read 31.8;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Oifice.

Signed and sealed this 10th day of January, A. D. 1950.

THOMAS F. MURPHY, Y

Assistant Oommz'asioner of Patents.

